Interference from fans in BT data cabinet?

[pxypxy308]

Landline has recently been affected by a constant electrical hum. Disconnecting everything and using the test socket on the master socket caused the hum to disappear.  Similarly, when the BT Smart Hub 2 is disconnected from the master socket or is powered off at the mains the hum also disappears.

Like me, the BT help desk couldn't decide if the problem was caused by a faulty hub or master socket, so arranged for Openreach engineer to visit.  He confirmed the hum, but after various tests was at a loss to explain it - until he mentioned that it might be "electrical interference from the fans in the BT data cabinet" 200m up the road - he claimed to have experienced this elsewhere. 

He went to check on the cab for at least 45 mins, and then returned to say that he would have to escalate the problem to the 'power team', and that this might take 2-3 days.  He said that there were 4 fans in the cab, and he thought that one might be faulty. 

Has anyone else heard of anything like this?  I know that fewer people have landlines these days, but can't believe that I'm the only consumer in a 200m radius of the cabinet to be affected, and if this is "a thing", why isn't it more commonly reported?

[Devon_Dave]

Sounds to me that the engineer has fobbed you off with that one. 

[DavidM]

HI @pxypxy308 and welcome.

Thanks for posting about your issue. I've not heard of a fan n a cabinet causing this type of problems before. You might have an electrical interference problem which is causing the problem. Take a look at REIN  for details on how to check that. Let me know how you get on.

Cheers

David

[yorkspark]

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@pxypxy308wrote:

Disconnecting everything and using the test socket on the master socket caused the hum to disappear.

This answers your own question, the test socket is connected to exactly the same pair as the rest of the socket, this engineer was talking pony. You either have a faulty master socket or more likely, a faulty psu on a phone,router or anything nearby causing interference.

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[pxypxy308]

Thanks - I did find it suspicious, but allowed for the fact that the Smarthub might be sensitive to electrical interference that the phone wasn't. It has now come to light that the Openreach engineer was less than truthful in his reporting back, so I have a new appointment booked with a different engineer, a £25 refund from BT and a complaint opened...

[pxypxy308]

Thanks - It has now come to light that the Openreach engineer was less than truthful in his reporting back, so I have a new appointment booked with a different engineer, a £25 refund from BT and a complaint opened... - I'll report back if/when this gets resolved!

[pxypxy308]

It has now come to light that the Openreach engineer was less than truthful in his reporting back, so I have a new appointment booked with a different engineer, a £25 refund from BT and a complaint opened... I'll report back in due course.

[Starwire]

A Humming Noise is usually caused by a Earth Contact, i.e. something causing one of the legs on the cable pair to Earth.

Earth Contact Faults could happen literally anywhere in the Network but I seriously doubt it would be caused by one of the DSLAM Cooling Fans.

Also REIN being induced into the line wouldn’t cause an Audible Noise you could hear.

[iniltous]

Was a replacement router ever supplied ?, the OP suggests it was considered as a possible cause of the issue but not if it were replaced, unless the original router in the test port ( along with the phone ) doesn’t ‘hum’ thus proving it OK, then the hub may be faulty

TBH , if everything is OK in the test port , and the issue only presents itself when the master socket is reassembled, then if any extension wiring /sockets exist then that may be the cause, or if to use the master socket test port the router was moved to a different electrical socket ( and it’s fine ) but plugged back  into the  mains socket where the router is normally sited the ‘hum’ comes back,  it may the mains socket itself , either way , generally if everything is OK at the master socket test port ,then  the issue isn’t really one for your provider or Openreach to resolve as the point at which responsibility ends is normally the test port  of the master socket, if  phone and broadband are fault free plugged in there , there then whatever the issue is it’s normally nothing to do with OR.

[pxypxy308 · Accepted solution]

My thanks to all who have contributed.  I won't go into all the details, but suffice it to say that my assessment that it was probably a faulty hub (not the power supply) was proven correct (after 13 DAYS of back and forth, and 2 missed engineer visits) and I eventually received a replacement, since when the line has been as quiet as it should be.  Apart from supplying the replacement, BT's contribution to the whole debacle was negligible.  I sent a 3.5 page letter of complain to BT, copied to the Head of Customer Services and have, as yet, heard nothing back.  Towards the end I felt pressured by BT personnel to close the complaint (presumably because it reflected badly in their stats).  I did close it, for the simple reason that there seemed little point in punishing them for a badly designed and operated system that was no fault of theirs (pun intended).